Quantumstate’s Blog

I was walking in the Cotswolds over the last couple of days and along the route I noticed an interesting phenomenon. There was a puddle of water which had some ice in it, since the temperature was pretty chilly, but what was unusual was that the ice was at the bottom of the puddle.

Ice normally floats so it tends to be on top of the water but in this case the ice must have frozen into some cracks in the ground which would have kept it locked in place. Then when some more water flowed over the top of it the ice couldn’t float up the the surface because it was stuck.

Unfortunately I did not have a camera with me at the time, otherwise I would have taken a photo of it. I haven’t noticed the effect at any other time. There was about 5cm of water above the ice.

If you have ever looked at water being poured or coming out of a tap you will probably have noticed the shape. The stream of water is wider at the top than the bottom. If you look carefully then you see the shape is a curve. The decrease is much more pronounced at the top than the bottom.

The reason for the shrinking width is fairly obvious. The water is falling under gravity so like everything that falls, it accelerates. This means that the water at the top is moving more slowly than the water at the bottom. We also know that the amount of water flowing stays constant. Virtually all of the water that leaves the tap reaches the sink below.

If the water is moving faster then for the same cross sectional area, more water will be flowing. Therefore because the flow stays constant the cross sectional area must decrease so the hence the width decreases.

Now all that is left is to explain why the shape is a curve rather than a cone shape. There are in fact two separate reasons for this.

Firstly the cross sectional area is inversely proportional to the velocity to maintain a constant flow. What you see, when you look at the flowing water from the side, is the width of the flow. This means that the velocity is inversely proportional to the square of the width. This will cause a curve.

The second reason is because the velocity increase linearly with time not distance. So the increase in velocity over 1 second will be the same at any point. However further down the water is moving faster so over that second the water have moved further. So over 1 cm the velocity will increase by a smaller amount at the bottom than the top.

One of the challenges in designing a program is to provide a user friendly interface for the user. If the program is too complicated then it will not be used as much. This has sometimes led to a reduction in how much the program can be customised and configured to the way the user likes it.

The main problem is, of course, that there are different users, who will each have a different amount of experience and expertise. Basic users will be confused by too many options yet more advanced users will want to be able to change many of the details to the way they want.

This is where I think the advanced options become useful. This removes the complicated configuration possibilities away from the basic users who will probably never look at the advanced options. Yet for the more advanced user there can be huge possibilities within the advanced configuration to do whatever they like.

I think this is probably the best way to deal with the conflict of keeping things simple and allowing for more advanced things. Now the only problem is working out what is simple enough to keep in the basic options and what is advanced enough for the advanced options.

Glest is one of the most advanced open source rts games. If you have not come across it before I would highly recommend downloading it and trying it out. It is fully 3D.

“The core game allows the player to take control of two completely different factions: Tech, which is mainly composed of warriors and mechanical devices, and Magic, that prefers mages and summoned creatures in the battlefield.”

The recently released 3.0 beta can be downloaded as either pre-compiled binaries for windows or as source code which you can compile for Linux. The main new feature is the much needed multiplayer which should allow for far more enjoyable games against good human opponents.

There have also been a few other minor improvements such as balancing. I am looking forward to trying this out, the download link is on their site

Yesterday I went to see a couple of Christmas lectures with my school. There was both a maths and a chemistry lecture. Both lectures were pretty good and they definitely made me look forward to what university might be like. Of course it is hard to tell because they covered some of the more fun content.

The chemistry was in the morning and was done by a couple of chemists from Southampton University. They did plenty of fun experiments. They started off with cryogenics so they had the dry and and liquid nitrogen to freeze things with. They lit a balloon full of oxygen and helium to show us a fast reaction which was pretty loud. Also they showed us some things which glowed. You really need to see things like this to appreciate them though, my description definitely doesn’t do them justice.

The Maths lecture was by David Acheson from Jesus College, Oxford. His talk was really interesting, he showed us some interesting proofs and little mathematical tricks. He has a website which has some of the things that he showed us on it. The programs that he has on there are quite fun to look at and fairly informative. He also plays the guitar and so he played a bit to us, he says that otherwise he wouldn’t get to play it to anybody.

Just to finish off here are a couple of the puzzles that he gave us to do over the interval. They are fairly common puzzles so you may have heard them before.

What is the value of sqrt(1+sqrt(1+sqrt(1+…))) with the square roots going on to infinity. The answer is best left in surd form since then it si clear you haven’t just used a pocket calculator.

If a spider is in the corner of a 1×1x1 cube and the spider wishes to reach the opposite corner how long is the shortest route. The spider can walk anywhere on a surface but cannot fly.

A while back I posted about having taken part in the senior mathematical challenge. I recently got the result back and discovered that I have managed to get through to the second round which is the British Mathematical Olympiad.

It is on this coming Friday and will be three and a half hours long. It contains 6 questions for you to answer and from the past paper they gave me they look very hard. I don’t think I will be getting beyond this stage but it should be fun taking part. Despite the rather long length of the thing. I am not sure I will ever take a test that is this long again in my life.

Anyway it should be good fun and I will update when I get the results.

I use firefox as my primary browser so I am naturally fairly interested in the development of firefox 3. I have installed a few of the alpha releases but now the firefox 3 beta has been released for download. There is a feature list on the mozilla website so I don’t really see the point in elaborating on that since theirs will be more complete.

The thing that I probably find most annoying about firefox currently is how the ram usage slowly creeps up, my PC is about 6 years old now and has 768mb of ram installed (I upgraded). This means speed is a fairly big issue currently. The beta seems to run pretty quickly and I was pleased to see the ram usage kept pretty low. There is a test page that I use which has a lot of css on it and that quickly moved the ram usage for about 50 - 120. When I then closed the tab I noticed that it only took a few seconds before the ram usage had dropped right down to the original.

There seems to be a bit of a bug with the canvas object because when I tried running my physics engine it messed up drawing the circles. Just squares were fine, and I am sure it was the drawing part that was going wrong because when I just changed the code that just drew the shape so it drew a square instead it worked fine. I submitted this to bugzilla and discovered that it was a fault in my code due to the canvas code that draws and fills the circle in firefox 3 being implemented slightly differently to firefox 2. It turned out that my code never finished drawing the arc (a 360 degree arc made the circle) so it ended up trying to draw hundreds of the arcs each frame which was why it got intolerably slow. The bug is now fixed.

Also firefox didn’t like being closed. It put my cpu at 100% for about one and a half minutes before the process actually ended. Hopefully this will get fixed since it is only beta 1.

Some of the features do look quite nice. I especially like the feature to pause downloads and then resume them even after you have closed the browser. Also the upgraded plugin manager is nice.

The best way to find out about it is to go and download the beta now and try it yourself.

A friend recently told me about a game called FreeRice. Basically they ask you for the definition of a word and for every word that you answer correctly 10 grains of rice are sent to help stop world hunger. As you get more words correct the difficulty level increases. The game gives you a vocab level so you can keep track and compare yourself to your friends. I ended up with a vocabulary level staying around 35/36, although with my parents helping we managed to get up to about 45 peaking at 47. The score is out of 50. The game checks how hard words are by looking at how many people have previously answered them correctly, this is similar to the 20Q method.

Since the site only tells you about the number of grains of rice I decided to investigate further and look at what the rice was worth in terms of how many people it could feed. Luckily I had access to Wikipedia which could provide all of the information that I needed.

Wikipedia already has a dedicated page on rice which helpfully tells us that 10000 grains are needed per person per day so that is 1000 correctly answered questions. That does seems like an awful lot of questions so this is clearly not the most efficient way to stop world hunger, a better method would be to get a part time job and just donate the money earned.

But that said, it is a fun game to play and of course it does help quite a bit if loads of people play it. There was story I heard about a man who walked along a beach where there were thousands of starfish washed up on the sand after a storm and he came across another man who was throwing some back into the sea. The first man asked the second why he bothered because he was hardly making any difference. The second man replied that it made a difference to the one that he threw back into the sea.

So although it may not seem significant on the large scale of the many millions who are near starvation but it does make a difference to somebody.

http://www.freerice.com/index.php

Yesterday I took part in the Senior Mathematical challenge. This is a test that is created by the UKMT (United Kingdom Mathematical Trust) which is designed to test your mathematical skills more than your actual knowledge. The paper lasts 90 minutes and is multiple choice. Unlike most exams if you get questions wrong you lose a mark however you gain 4 marks for every question you answer correctly. Since there are 5 choices per question you are likely to end up with negative marks for randomly answering questions. This is so that people work them out rather than randomly guessing at the end.

The UKMT have a website which has a few past papers on it including the one that I did. I will post again when I find out my result. I have done the tests in three previous years, Twice with the junior and once with the intermediate. I have done 2 junior second rounds and 1 intermediate so perhaps I might get through again, but I am not sure because it is meant to be quite a bit harder. The paper is 3 1/2 hours long for the second round though.

I’m not a designer at all really, I’m more of a coder. I was thinking about redesigning this blog because I have the default but I would like to make a custom one. I have thought about it and I really don’t seem to be able to come up with any ideas on what it should look like. I feel that if somebody told me what they would like their website to look like then I could have a fair go at making it for them, since I am ok at drawing stuff although not amazing. I just can’t seem to do anything when faced with a completely blank canvas so to speak.

I don’t really think that design is all that important anyway so I am not too bothered about not being able to reskin this. My thoughts are that the design is meant to be nice to look at but it is an extra thing, not the main attraction. people go to my site to look at the content. If the content is good then they will like my site and come back to it. So the design can’t get in the way of the content at all.

Even so when I visit websites I do realise that I am influenced by the design. I do value the content far more than the design but it does influence me as it must do with everybody else.

This reminds me of basically the only main feature that IE7 has that firefox does not which is the tab preview thing where you see the contents of all of the tabs in little pictures so you can see them at a glance. Although I said you can see the contents I didn’t really mean that. You cannot see the content, it is far too small to read, you get a preview of the design.

In the example demo video that I saw about IE7 the guy demonstrating did a search, then opened a load of the links as background tabs. He then proceeded to go to the tab preview thing and then select the ones he wanted. In my opinion this is just plain stupid. The little extract of text that is given to you by the search engine is clearly far more informative than the design of the web page. How pretty a site is doesn’t mean it has good content because the content is completely separate. Loads of sites get other people to make their design for them and then they add the content themselves, so the content could still be awful.

You can probably see from the quantumstate website that I have a view like this since I am sure that the design isn’t really very amazing, I am far more interested in writing the content for it than making it look really pretty. I did do the design myself. I am fairly pleased with it but I don’t think it is all that good.

Maybe I will manage to get a reskin done sometime for this blog but as I have said it isn’t a high priority.